Various apparatuses have been devised heretofore to feed a product in which an inner viscous food material is enveloped with an outer viscous food material. One type of known apparatus is found and incorporated in the "Rheon Encrusting Machine," manufactured by the assignee of the present application. It is generally described in "The Operation Manual for Rheon Encrusting Machine," published in January 1969 by the assignee.
Such an apparatus includes a housing in which a plurality of vertical rollers mounted for rotation within the housing are arranged in a circular array. The axis of rotation of each of the rollers is tilted in one direction in such a way that an inner space surrounded by the rollers forms an inverted cone-shaped cavity for receiving the outer food material. The narrow bottom of the cavity is formed as an outlet defined by the lower ends of the rollers. The outer material received within the cavity is fed to the outlet while the outer material rotates in the cavity by the rotation of the rollers. The apparatus also includes a vertically extending rotary duct, which is rotatably placed in the center of the cavity, for rotatingly feeding the inner food material. The bottom of the duct forms an outlet, which is aligned with the roller-cavity outlet in a coaxial relation. An adhesion section for causing the peripheral surface of the inner food material to be able to adhere to the inner surface of the outer food material is formed between the two outlets. At the adhesion section, the rotating velocity of the inner food material relative to the outer food material can be reduced, since the duct can rotate.
In operation, the operator feeds a desired mass of the outer food material into the cavity. The outer material thus deposited within the cavity is then downwardly fed through the adhesion section and then is made to pass through the cavity outlet by the rotation of the rollers. Simultaneously, the inner material is fed to the adhesion section through the duct and its outlet, with the inner food material rotating together with the duct. Since the outer food material and the inner food material are viscous, the inner surface of the outer food material adheres to the peripheral surface of the inner material with the help of the rotation of the outer food material at the adhesion section.
As the result, the bonded outer food material and inner food material form a unified body and are downwardly extruded from the apparatus as an elongated product in which the outer material envelops the inner material.
One problem faced in the production of the enveloped product in the prior art is that the outer surface of the duct sticks to the outer food material. The result of this is a build-up of the outer material on the outer surface of the duct which interferes with the effectiveness of the feeding of the outer material from the cavity to the adhesion section. Hence, the prior-art apparatus is faced with a decrease in the productivity of the enveloped product. This problem may often occur where the outer material is a highly viscous material, such as a rice-based material.
Accordingly, there is, a need in the art for a feeding apparatus that has a more enhanced productivity of the enveloped product, and which is applicable to an outer food material having a high viscosity.